1. Field of the Invention
The present invention relates to correction optical devices that correct image shake caused by shaking of optical devices, in particular, to a correction optical device equipped with a holding mechanism.
2. Description of the Related Art
Correction optical devices equipped with a correction optical system are known. The correction optical system prevents image shake by causing a compensation lens to perform a translational movement in a plane perpendicular to the optical axis. Some of the correction optical devices are equipped with a holding mechanism. This holding mechanism, when image shake correction is not performed, regulates movement of a movable portion and secures the movable portion that has the compensation lens.
For example, Japanese Patent No. 03397536 discloses a correction optical device. In this correction optical device, by rotating a lock ring 719, protrusions 75f of a supporting frame 75 of the compensation lens is engaged with an inner peripheral surface of the lock ring 719 in order to regulate movement of the compensation lens.
U.S. Pat. No. 7,755,666 discloses a correction optical device. In this correction optical device, when a movable member 14 having retaining portions 14a rotates to a specified position, the retaining portions 14a are engaged with engaging protrusion receiving portions 15a in order to retain the movable member 14. Thus, movement of the compensation lens is regulated.
According to Japanese Patent No. 03397536, in order to change the state of a movable portion including the compensation lens from a secured state to a movable state, that is, to a state in which correction is allowed, a driver that rotates the lock ring 719 is required. Furthermore, a separate actuator is required in order to hold the lock ring 719 in the state in which correction is allowed. This can increase the size and the cost of the device.
According to U.S. Pat. No. 7,755,666, a driver that causes the movable member 14 to rotate also drives a translational movement for image shake correction.
Today, there is a demand for optical devices such as, for example, digital still cameras and digital video cameras that have reduced sizes while realizing improved image quality. In order to meet this demand, alignment of axes, that is, adjustment of positions for alignment of optical axes is required in a section of an optical system having high sensitivity to eccentricity. In this adjustment, the optical axes of lenses are aligned with each other in order to eliminate eccentricity.
According to a method disclosed in U.S. Pat. No. 7,755,666, alignment of axes is performed so as to eliminate eccentricity. However, when image shake correction is not performed, the compensation lens is rotated. Thus, the optical axes having been aligned with each other are shifted from each other, and accordingly, image quality is degraded.
Furthermore, in order to switch the state of image shake correction from a correction state (a state in which the compensation lens is movable) to a non-correction state (a state in which the compensation lens is locked), it is required that an electrical current flow in drive coils. Thus, a manual switcher is provided for a case in which an electrical current cannot flow for a reason such as a battery has run out of power.
In a manual switching operation, according to the method disclosed in U.S. Pat. No. 7,755,666, it is required that a manual retaining member 52 be rotated to a specified position. However, when an operator has not fully rotated the manual retaining member 52, the compensation lens cannot be secured. In this state, if a large shock occurring at such a time as when the compensation lens falls off is applied to the correction optical device, the correction optical device may be damaged.